Programming is independent from language
(A) COBOL supports many vital processes
So don't try to squish it through a mincing machine and trust it.
(B) The bad news is it's been working for a little long.
Longevity is not a sign of weakness, a lack of headcount knowledgeable in COBOL is the problem.
(C) "If you can find a COBOL programmer, they are expensive..." + there are billions of lines of COBOL code...
Sounds like a reason for learning COBOL for some, it's a supply/demand no-brainer.
Programming consists of logic with one of three choices in program flow: sequence; condition and iteration. All programming logic follows this, and all languages accommodate it. If you're a programmer, you can code your program in any language you know .
Converting code autonomously is essentially starting from scratch, autonomous reverse engineering, without the human taking hands-on until testing - that won't leave any bugs. (Hugely impacts A)
If (A) is important, you really don't want to risk this approach, it creates a mind fuck.
(B) appears to be/is the case because of FOTM, it's chic to code in Python/Rust/Java... or whatever. It doesn't matter.
If you combine (A), (B) and (C) it's clear that's what is "needed" is for more COBOL coders, not a farcical "AI" fix. (A) because the $Corps should stop fucking about and help themselves by not scrimping, and (C) benefits the programmer. They combine to (B).
 If that's not the case, it's beyond the scope of the significant context.
 If it's the right language for the job.